Heater Cable, Bus
| 1951 (starting at chassis # 20-014685) - 1955 (through chassis # 20-117903) | BOTH | |
| 1955 (starting at chassis # 20-117903) - 1967, non walk-thru models only | BOTH | |
| 1955 (starting at chassis # 20-117903) - 1967, walk-thru models only | BOTH | |
| 1968-1971 | LEFT | RIGHT |
| 1972 | LEFT | RIGHT |
| 1973-1979 | LEFT | RIGHT |